Usually catalysts for these processes are active metals, oxides or salts deposited on supports that are amorphous or crystalline oxides of 2, 3, 4 Group elements, for instance, supports based on silica, which are characterized by high chemical and thermal stability, by the possibility of controlling within a wide range the specific surface and porous structure thereof, and of making products of various shapes: powders, cylindrical or spherical granules, single- or multi-channel monoliths, woven and nonwoven materials manufactured from fine fibers.
The most important functions of the support are the providing of a highly active state of deposited catalytic components and maximum complete utilization of the catalytic properties of these usually costly components.
This is achieved:                by maximum dispersion of catalytically active substances and by optimal distribution thereof over the surface or in the surface layers of the support;        by the effect produced by the support on the chemical and electronic state of the catalytic component to increase its performance thereof;        by increasing the effectiveness factor by using an optimal porous structure which ensures good mass transfer of substances participating in the catalytic reaction, and also by employing supports having optimal shapes: rings, multi-channel monoliths, fibrous structures manufactured in the form of woven and nonwoven materials, wool, cardboard, etc.        
The most widespread method of dispersing a catalytic component is the use of supports with a high specific surface and a sufficiently high interaction with an active component, precluding the surface diffusion and growth of the particles of the latter. Different processes have been developed for the synthesis of siliceous supports with a high specific surface, for instance, hydrolytic precipitation of silica from inorganic and organic silicon compounds, yielding very small particles (R. K. Iler, The Chemistry of Silica, Moscow, Mir Publishers, 1982, vol. 1, p. 706). However, as a rule, highly dispersed supports are characterized by a fineporous structure, which leads to reducing the effectiveness factor deu to pore diffusion restrictions.
Another technique for providing siliceous materials with a high specific surface is selective acid extraction of non-silica components from multycomponent silicate materials, e.g., from silica glasses. The acid-insoluble silica skeleton makes up porous systems with a large specific surface, so-called porous glasses (S. P. Zhdanov. //Zhurnal VKhO im. Mendeleeva, 1989, vol. 34, No. 3, pp. 298–307). The value of the specific surface area, the pore size and volume substantially depend on the conditions of leaching out, as well as on the composition and pre-treatment of starting glasses, which determine the homogeneity of heteroatoms distribution and the formation of micro-heterogeneous areas under liquation. As a rule, in leached glasses micro- and mesoporous structures are formed (Rpore<100 Å). Like in conventional supports, the presence of small pores may reduce the effectiveness factor. The providing of larger transport pores of the support substantially lowers its mechanical strength, especially when fine-fiberglass materials are used, and therefore special techniques are required in the preparation (U.S. Pat. No. 4,933,307, IPC C03C 11/00, C03C 12/00, 1990).
In most cases it is preferable to use coarsely sufficiently strong and nondispersed supports of optimal shapes, but for achieving high-activity states of catalytic components thereon it is necessary to carry out additional modifications of support. For instance, honeycomb monoliths or glass fiber woven materials are used, to which comparatively thin layers of highly dispersed oxides are deposited, which are catalysts (U.S. Pat. No. 4,038,214, IPC B01J 23/86, B01J 23/84, B01J 35/06, 1977) or serve as a support for deposition more valuable catalytic components, noble metals inclusive (U.S. Pat. No. 5,552,360, IPC B01J 21/04, 21/08, 1996; U.S. Pat. No. 5,155,083, IPC B01J 21/06, B01J 21/08, 1992). However, such techniques complicate the technology of catalysts preparation and, correspondingly, make it more expensive.
Catalytic components deposited on non-modified supports are characterized not only by their low initial dispersity, but also by insufficiently strong binding with the support, which causes high surface mobility of catalytic substances, leading to their agglomeration during operation, as well as to peeling off the surface and possible entrainment by the gas flow even in the case of medium-temperature catalytic processes. This was observed, when active metals were deposited on glass fiber woven supports. In order to eliminate this disadvantage, in RU Patent No. 2069584 (IPC B01J 23/38, 23/70, 1996) for increasing adhesion of catalytically active metals to the surface of the support at the early stages of its synthesis, the composition of the support is varied. To do that, dopping additives also from catalytically active metals and/or oxides thereof are incorporated into the support manufactured in the form of threads, fibers, woven and nonwoven materials from silicon and/or aluminum oxides. Dopping additives are used as a raw materials for preparing melt based on silicon oxide. The support fibers thus made are further subjected to weaving and leaching operations, and after that a catalytic component is deposited on the surface of the woven material.
This process is disadvantageous in a considerable part of metal being localized in the bulk of the glass fiber, and, consequently, in ineffective utilization thereof in catalysis, as well as in possible technological losses of valuable metal at the early stages of incorporating thereof. It may be supposed that dopping additives incorporated at the early stages into the bulk of the glass support cause a change in the support structure and assist in the formation of certain structures which are responsible for catalyst performance.
One of the types of structures of a silica-rich support, providing the formation of highly active catalytic species, is proposed in the present invention.